1. Technical Field
The present invention relates to a variable speed transmission assembly and, in particular, to such an assembly for use in a vehicle such as a lawn tractor.
2. Description of the Prior Art
U.S. Pat. No. 3,759,342 describes a lawn tractor having a variable speed drive assembly. The drive assembly includes a variable speed pulley mechanism supported on a bracket arm that pivots on a pin fixed to the frame. The bracket arm has a slot that receives the pin. The bracket arm slides relative to the pin, with the pin moving in the slot, to effect a second degree of movement of the variable speed pulley mechanism. The pin can sometimes become stuck in the slot, in a manner that prevents proper operation of the variable speed assembly.
The present invention is a vehicle drive assembly including a directional control transmission assembly operable between a forward drive condition and a reverse drive condition, and a variable speed drive assembly. The drive assembly also includes a transmission drive belt extending between the variable speed drive assembly and the directional control transmission assembly to transmit force from the variable speed drive assembly to the transmission assembly when the transmission assembly is in the forward drive condition and when the transmission assembly is in the reverse drive condition. The drive assembly also includes a main drive belt extending between the variable speed drive assembly and a source of power to transmit force to the variable speed drive assembly.
The drive assembly further includes a linkage assembly which is operable to move the variable speed drive assembly toward the directional control transmission assembly to change the variable speed drive assembly from a first condition in which the directional control transmission assembly is driven at a relatively low speed by force transmitted from the variable speed drive assembly to the directional control transmission assembly through the transmission drive belt and a second condition in which the variable speed drive assembly is effective to drive the directional control transmission assembly at a high speed.
In one embodiment, the linkage assembly includes an eccentric mechanism. In another embodiment, the linkage assembly includes a linkage arm. Other features of the present invention include a brake that is automatically operative by movement of the manual speed control to a slow/stop position, a reverse speed limiter, and the ability to manufacture and sell the vehicle drive assembly as all one unit for installation in a vehicle such as a lawn tractor.